LTC3714_15 Datasheet, PDF (23/28 Pages) Linear Technology – Intel Compatible, Wide Operating Range, Step-Down Controller with Internal Op Amp

LTC3714
Applications Information
Solving for this resistance value:
R_VP
=
V_OUT ΔI_TH
(0.6V)g_m ΔV_OUT
= ^{(1.15V)(1.08V)} = 20.3k
(0.6V)(1.7mS)(60mV)
The gain setting resistance R_VP is implemented with two
resistors, R_VP1 connected from I_TH to ground and R_VP2
connected from I_TH to INTV_CC. The parallel combination of
these resistors must equal R_VP and their ratio determines
nominal value of the I_TH pin voltage when the error ampli-
fier input is zero. To set the beginning of the load line at
the regulation point, the I_TH pin voltage must be set to
correspond to zero output current. The relation between
voltage and the output current is:
I_TH(NOM)
=
⎛ _12V
⎜
⎝
V_RNG
⎞
⎟R_SENSE
⎠
⎛⎝⎜_IOUT
–
1
2
ΔI_L
⎞
⎠⎟
+
0.75V
=
⎛
⎝⎜
12V
0.5V
⎞⎠⎟_(0.003Ω)
⎛⎝⎜_0A
–
1
2
5.4A^{⎞⎠⎟}
+
0.75V
= 0.55V
C_SS
0.1µF
R_RNG1 R_RNG2
10k 90.1k
R_PG
100k
9
VID2
8
VID1
10 _RUN/SS
VID0 ⁷
11
V_ON
12
PGOOD
BOOST ⁶
5
TG
13 _VRNG
SW ⁴
D_B
CMDSH-3
C_B
0.33µF
C_C1
2.2nF ^RC
20k
C_ION 0.01µF
R_VP2
185k
R_VP1
23k
LTC3714
14
I_TH
C_C1
100pF ₁₉
SGND
SENSE ³
2
PGND
C_FB 100pF
21
I_ON
22
V_FB
BG ¹
28
INTV_CC
20
FCB
V_IN ²⁷
23
26
V_OSENSE EXTV_CC
5V
R_ON
330k
INTV_CC
0.1µF
24 _VID3
15 _OPVIN
16 _{OP –}
VID4 ²⁵
OPOUT ¹⁸
OP ^{+ 17}
C_VCC
4.7µF
R_F
1Ω
C_F
0.1µF
M1
L1
IRF7811 0.68µH
M2
IRF7811
×2
D1
UPS840
R_SENSE
0.003Ω
V_IN
C_IN
7V TO 24V
10F
25V
×3
V_OUT
1.15V/15A
C_OUT
270µF
2V
×3
C_IN: UNITED CHEMICON THCR70EIH226ZT
C_OUT: PANASONIC EEFUE0D271
L1: SUMIDA CEP125-4712-T007
3714 F08
Figure 9. CPU Core Voltage Regulator with Active Voltage Positioning 1.15V/15A at 300kHz
3714f
23